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Total deviation on both sides to take into account = 1.5*0.3 = 0.45 so range wud be (8.1-.45) to (8.1+.45) which gives answer in 10 seconds!!

@felixlagemann8109

7 жыл бұрын

true story bruff

@21MilesAhead

Жыл бұрын

we got a harvard genius innit fam, go get this nigga a diploma cuh

After watching about 8 videos of SD I could finally found what I needed to know! Thank You!

@dominatethegmat

8 жыл бұрын

Awesome, so glad this video was clear for you!

Nowhere in the question does it say the values are normally distributed about the mean.Simply find the range and the number of values. No need to draw a graph here.

Nicely explained!

Nicely done.

It was so useful Brett... Thank you.. finally understood what S.D is ...!

@dominatethegmat

5 жыл бұрын

Awesome, I'm glad this video helped you have a breakthrough!

thank you

@dominatethegmat

11 күн бұрын

You're welcome. Glad it helped!

Well explained..thanks brother

@dominatethegmat

5 жыл бұрын

My pleasure, glad it helped!

This helps more than school

Thanks a lot, sir, you are so helpful! I comprehended everything except 34%, can you please explain how you found it? Since I have no idea

@dominatethegmat

2 жыл бұрын

I'm glad you're finding my videos helpful! The 34% comes from recognizing that 68% of outcomes in a normal distribution fall within one standard deviation of the mean. For the purposes of the GMAT, don't worry about where that comes from -- just memorize it. So for this particular question, one S.D. around the mean is from 7.8 - 8.4. Of the outcomes within that range, half fall below the mean and half fall above the mean. Half of 68% is 34%.

@amrahabbasov5267

2 жыл бұрын

@@dominatethegmat Thanks a bunch sir🙂

I have one question: how did you get the 34%?

@dominatethegmat

10 жыл бұрын

It's just something you need to memorize. There's a mathematical proof for percentage of outcomes that falls within one standard deviation of the mean, but it's beyond the scope of the GMAT. Just memorize that 68% of outcomes fall within 1 S.D. of the mean, which when you divide that by 2, that's 34% that is either 1 S.D. above or below the mean. Does that help?

@buggieboi1988

10 жыл бұрын

Dominate the GMAT It sure does. Thanks a lot for taking the time to reply Brett. I appreciate it.

how did you get 1.5 standard deviations of .3 is .15? isn't it .45?

@dominatethegmat

5 жыл бұрын

You're correct, it is .45 total from the mean of 8.1. That's why I'm finding the number of data points that fall below 8.55 on the high end (8.1 + 0.45) and above 7.65 on the low end (8.1 - 0.45). The 1.5 is what the question itself is asking about. I didn't come up with that, that's from the question itself. They're asking about 1.5 standard deviations from the mean, which as you indicated is 0.45 ounces.

@27gio92

3 жыл бұрын

@@dominatethegmat It's probably because i miss same background knowledge but how can you say 0.3 is "one standard deviation?"common sense would say 1 is "one standard deviation". Anyway great content

@dominatethegmat

3 жыл бұрын

@@27gio92 I'm glad you enjoy my content! The actual value of "one standard deviation" above/below the mean is specific to the data points being analyzed and varies from data set to data set. For example, if I collect the heights of 30 students in a class, I might find that they have an average height of 68 inches with a standard deviation of 3 inches. How did I get "3 inches" as the value of "1 standard deviation?" I would have calculated it by plugging all 30 heights into the standard deviation formula. Fortunately you don't need to actually know that formula for the GMAT, but you do have to know how to interpret what a standard deviation means. Here, in this question, they've given you the standard deviation as equal to 0.3 ounces. How did they arrive at that? Who cares! Just go with it 😀.

Hello dear! I just did not understand why you said half of the point 0.3 in the video? And why do we have to multiply 0.3 by 1.5 or how did you get the number 0.15??

@dominatethegmat

3 жыл бұрын

We're told that one (1.0) standard deviation = 0.3 ounces. But we're asked about 1.5 standard deviations, not just 1.0 standard deviation. So if 1 S.D. = 0.3, then 1.5 S.D. = 0.3 plus another half of a standard deviation, or 0.3 + (0.3)(1/2) = 0.3 + 0.15 = 0.45. The 0.15 is that extra half of a standard deviation.

@tamarchaghlasian9755

3 жыл бұрын

@@dominatethegmat Thank you!

Easy one

@dominatethegmat

Жыл бұрын

Nice!

Is the question is clear ? It says 1.5 standard deviation. Why it's not clearly mentioned 1.5 times?

@dominatethegmat

5 жыл бұрын

I'm not sure I understand your question. Can you please clarify?

@wilsonvinas5906

5 жыл бұрын

1.5 standard deviations is the same as 1.5 multiplied by the value of the standard deviation. So if it were to say 2 standard deviations from the mean, you would add 2(.3) to 8.1 to find the upper value and subtract 2(.3) from 8.1 to find the lower value. Then you would count any values that fall within this region to find your answer.

@dominatethegmat

5 жыл бұрын

@@wilsonvinas5906 Well said.

@ValeriyKucherenko

5 жыл бұрын

GMAT questions are often constructed in a "misleading" way

why 34% and why 0.15 ? so many questions

@dominatethegmat

2 жыл бұрын

34% is half of the 68% that represents the amount within 1 S.D. under the curve. The 0.15 is half of 1 S.D., which we need since we're asked about 1.5 standard deviations, not just one.

600-level question.

@Pickledfeet165

5 жыл бұрын

econdoc lol

I dont think the concept you using is correct . 1.5 SD means 8.1 +/- (1.5×03) data with in this range

@dominatethegmat

3 жыл бұрын

That's exactly what I did in this video. 1.5 * 0.3 = 0.45. When you +/- that to 8.1, that gives you a range from 7.65 to 8.55. We then counted up the number of data points within that range to arrive at the answer. Now, I took the intermediate step of talking about +/- 1SD around the mean for teaching purposes. But then we expanded the range to +/- 1.5SD before determining the final answer.